Esophageal recording/pacing catheter with thermistor and cardiac imaging transceiver

ABSTRACT

A single use disposable esophageal electrode structure is formed with a planar sheet body member. The body member carries a plurality of spaced-apart conductive electrode members. A temperature sensor can also be carried on the body member. A layer of adhesive on the body member can be used to affix it to an esophageal probe. A plurality of conducting members is coupled to the body member. Each of the conducting members is in turn coupled to a respective one of the electrodes. A free end of the conducting members carries an electrical connector for connection to other electrical units.

This application is a division of application Ser. No. 07/608.200 filedNov. 2, 1990, now U.S. Pat. No. 5,199,433, which is acontinuation-in-part application of Ser. No. 306,997 filed Feb. 6, 1989,now U.S. Pat. No. 5,069,215, and entitled Multiple Electrode AffixableSheet.

FIELD OF THE INVENTION

The invention pertains to non-invasive cardiac sensing or stimulating.More particularly, the invention pertains to an apparatus and a methodfor non-invasively recording/pacing a subject's heart whilesimultaneously performing cardiac imaging.

BACKGROUND OF THE INVENTION

It has been recognized that esophageal electrodes are particularlyuseful in connection with non-invasive esophageal pacing. One suchelectrode is disclosed for example in co-pending and commonly assignedU.S. patent application Ser. No. 930,748, now U.S. Pat. No. 4,817,611,entitled Improved Esophageal Electrocardiography Electrode.

It has also been recognized that transesophageal electrocardiography canbe used for the purpose of studying myocardial ischemia. One such systemis disclosed in commonly assigned and copending U.S. patent applicationSer. No. 267,459 entitled Method and Apparatus For Detection ofPosterior Ischemia.

It has also been recognized that transesophageal echocardiography can beutilized for the purpose of detecting or evaluating, among otherconditions, myocardial ischemia. A particular transesophageal imagingprobe is disclosed in U. S. Pat. No. 4,834,102 to Schwarzchild et al. asdescribed in Schwarzchild et al. The transceiver for the imaging probecan be positioned in the esophagus or the stomach of the individualwhose heart is being studied.

It would be desirable to be able to combine the pacing capability ofesophageal electrodes and the imaging capability of echocardiographyprobes into a single unit so as to be able to stress the heart and tosimultaneously study its characteristics.

SUMMARY OF THE INVENTION

An apparatus and method are provided for esophageal heart pacing andcardiac imaging. The apparatus has a flexible plastic sheet member. Thesheet member, which can be generally of a rectangular shape, carries aplurality of spaced-apart electrode members.

A layer of adhesive is carried on the opposite side of the sheet memberfrom the electrodes. Each of the electrodes is connected to one memberof a plurality of insulated wires or traces.

The insulated wires can be formed on an elongated mylar sheet memberwhich is affixed at one end to the sheet member. At the other end of theelongated mylar sheet member is an electrical connector which is in turnconnected to each of the conductors of the sheet member.

The sheet member can be removably attached to a cardiac imaging probe.As an alternate to a layer of adhesive, other means, such as using a"cling vinyl", can be used to attach the sheet member to the probe.

The electrical connector can in turn be coupled to a switch forselecting various pairs of electrodes. Outputs from or inputs to theselected pair of electrodes can be coupled to or received from anelectrocardiograph or an esophageal pacing unit.

Signals from the esophageal pacing unit can be applied to the selectedpair of electrodes for the purpose of non-invasively pacing the heart ofthe subject. Alternately, signals from the selected pair of electrodescan be provided to an amplifier for further processing for the purposeof driving the electrocardiograph.

A temperature sensor, such as a thermistor, is carried on the sheetmember. Conductors to/from the temperature sensor are carried on theelongated mylar sheet member.

A method of esophageal cardiac imaging of a subject's heart includes thesteps of:

optimally locating a cardiac imaging transmitter in the esophagus;

pacing the heart from an optimal location in the esophagus; and

monitoring the temperature of the subject from the esophagus.

The method can also include steps of recording and selecting anelectrode configuration for maximum P wave deflection.

The present esophageal electrode unit is especially advantageous in thatit can be manufactured as a single use element which can be affixed to areusable echocardiography probe prior to use. After use, the electrodeunit can be discarded. Alternately, the presentmulti-electrode/temperature sensor structure could be permanentlyaffixed to an esophageal echocardiography probe.

Numerous other advantages and features of the present invention willbecome readily apparent from the following detailed description of theinvention and the embodiments thereof, from the claims and from theaccompanying drawings in which the details of the invention are fullyand completely disclosed as a part of this specification.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partial, side, schematic view of a subject illustrating therelationship between a probe in accordance with the present inventionand the heart of the subject;

FIG. 2 is an enlarged portion of a probe carrying a multi-elementelectrode in accordance with the present invention;

FIG. 3 is an elevational view of one side of a disposablemulti-electrode esophageal unit;

FIG. 4 is a second view of the disposable multi-electrode esophagealunit of FIG. 3;

FIG. 5 is a sectional view taken along plane 5--5 of FIG. 1;

FIG. 6 is a pictorial diagram of an electrode selecting switch inaccordance with the present invention;

FIG. 7 is an enlarged, fragmentary, perspective view of anotheraffixable sheet in accordance with the present invention;

FIG. 8 is a sectional view taken along plane 8--8 of FIG. 7;

FIG. 9 is an enlarged, side elevational view of an affixable sheetcoupled to a block diagram representation of an associated electricalsystem.

FIG. 10 is a perspective view of yet another embodiment of a disposablemulti-electrode esophageal unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawing and will be described herein indetail specific embodiments thereof with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not intended to limit the inventionto the specific embodiment illustrated.

FIG. 1 illustrates a subject S having a heart H and an esophagus E witha probe 10 positioned therein. The probe 10 carries a disposableesophageal electrode structure 12. The structure 12 is formed with aflexible medical grade plastic base member 20. The base member 20carries a plurality of spaced-apart conducting elements 22-32 on asurface 20a.

Each of the elements 22-32 is formed of a bio-compatible conductingmaterial. Each of the elements 22-32 is permanently affixed to the basemember 20. The base member 20 on a surface 20b opposite the surface 20acarries a layer of adhesive 34. The layer of adhesive 34 is used toaffix the member 20 to the reusable probe 10.

The adhesive layer 34 can be formed of any bio-compatible adhesive withadequate strength so as to fix the electrode structure 12 to the probe10 for the length of any desired procedure. Subsequent to completion ofthe desired procedure, the electrode structure 12 is removed from theprobe 10 and disposed of. The probe 10 can then be sterilized andreused.

A plurality of conducting members 36 is attached in a region 38 to themember 20. The plurality 36 can be formed with a plastic base member 40on which is deposited a plurality of spaced apart conducting traces36a-36f. Each of the traces, such as the trace 36a is electricallyconnected to a respective one of the conducting members 22-32, such asthe member 22.

It will be understood that the details of the formation of the traces36a-36f and the way in which those traces are carried by the plasticmember 40 are not limitations of the present invention. Similarly, thedetails of how the traces 36a-36f interconnect with the conductingmembers 22-32 are also not a limitation of the present invention.

A second end of the plurality 36 carries an electrical connector 40 of aconventional variety. The connector 40 can be mated with a correspondingconnector 42 which is carried by a multiple conductor cable 44. Thecable 44 is in turn coupled to a manually operable switch 46.

The switch 46 could for example be implemented as a two-polemulti-position switch. It will be understood that the exact details ofthe switch 46 are not a limitation of the present invention. The switch46 is used to manually select a pair of electrodes from the plurality22-32. Output from the selected pair of electrodes, or input thereto, ona two-conductor cable 48 can be coupled to an ECG or received from anesophageal pacing unit 50.

The disposable multi-electrode element 12, in combination with the probe10, makes it possible to combine cardiac pacing as a form of stresssimultaneously with echocardiography to determine and sense heartfunction. For example, if the probe 10 is a commercially availabletransesophageal ultrasonic probe such as a Hoffrel Instruments, Inc.Model 482 or a Hewlett-Packard Model 21362A.

The electrode structure 12 can be used for pacing the left atrium of theheart H. Simultaneously, an ultrasonic transmitter and receiver 52 onthe probe 10 transmits ultrasonic waves toward the heart H and sensesultrasonic reflections therefrom for the purpose of forming an image ofthe cardiac chambers as the heart H is being simultaneously stimulated.

In a typical procedure, the sheet electrode member 12 is affixed to theparameter of the probe 10 using the layer of adhesive 34. The electrodestructure 12 is located at a level about 10 centimeters above theultrasonic transmitter and receiver 52 in the probe.

The ultrasonic transmitter/receiver 52 is carried at a distal end of theprobe 10. The multi-electrode element 12 is carried on the probe 10adjacent the transmitter/receiver 52 but spaced therefrom toward theproximal end of the probe 10.

The probe 10 is inserted in a conventional fashion into the esophagus Eof the subject S. The transmitter-receiver 52 is then positioned in theesophagus E optimally located to carry out the cardiac imaging function.

With the transmitter-receiver 52 optimally positioned, the optimalelectrode or electrodes from the plurality 22-32 can be selected usingthe switch 46. Since the plurality of electrodes 22-32 is carried on thecatheter 10, displaced away from the transmitter-receiver 52 toward theproximal end or connector 40, one or more of the members of theplurality will be optimally located adjacent the posterior surface ofthe heart H to carry out the desired recording and/or pacing function. Apacing unit, coupled to the cable 48, can then be used for pacing theheart H simultaneously with carrying out a cardiac imaging function.

By way of example and not by way of limitation, the width of each of theelectrode members 22-32 can be on the order of 5 or 7 millimeters with acorresponding spacing of 2.0-2.5 centimeters. The length dimension ofthe sheet member 20 can be in a range of 5-20 centimeters and the widthdimension can be on the order of 40 millimeters.

The length of the plastic extension member 40, which could be formed ofmylar or vinyl can be on the order of 50-60 centimeters. The body member20 can also be formed of a mylar or vinyl sheet. It will be understoodthat any medical grade plastic could be used for the body member 20without departing from the spirit and scope of the present invention.

Further, in a typical installation the switching unit 46 can beconnected so as to switch as electrode pairs, electrodes 22, 32; 24, 30;or 24, 26. If desired, other pairs of electrodes could be switched suchas, 22, 24; 24, 26; 26, 28; 28, 30; or 30, 32. If desired, additionalelectrodes can be formed in base member 20.

Alternately, the multiple electrode system 12 can be fabricatedpermanently attached to an imaging probe. Imaging probes, of the typediscussed above, usually include an ultrasonic transmitter and receiverlocated at the end of the probe.

The transmitter is located in the esophagus below the heart and isoriented on the probe to transmit toward the heart. Reflected ultrasonicwaves are detected by the transceiver, converted to correspondingelectrical signals and transmitted from the probe to outside analysiscircuitry.

Hence, it will be understood that the multiple electrodes 22-32 could bepermanently attached to the body of the esophageal ultrasonic probe asgenerally indicated in FIG. 1.

FIG. 7 and 8 illustrate an alternate single use disposable sheetelectrode structure 60. The structure 60 includes a flexible, generallyrectangular, planar plastic base member 62. Formed on the base member 62is a plurality of spaced apart metal electrodes 64a-64e.

Each of the electrodes 64a-64e is coupled to an elongated conductingmember, such as the respective members 66a-66e. The elongated conductingmen, hers 66a-66e are carried in part on the planar member 62 and inpart on an extension 62a thereof. The elongated conducting members66a-66e can be terminated at a connector, such as the connector 40 at aproximal end of the probe 10.

Also carried on the sheet member 62 is a temperature sensor 70. Thetemperature sensor 70 can be, for example, a thermistor. Elongatedflexible conductors 72 carried in part on the sheet member 62 and inpart on the sheet member extension 62a extend from the thermistor ortemperature sensor 70 to the proximal end connector 40.

As illustrated in FIG. 8, the planar sheet member 62 carries on one sidethereof a layer of adhesive 74. The structure 60 is removably attachableto the echocardiography probe 10 using the adhesive layer 74.

Alternately, the base member 62 can be formed of a so-called "clearcling vinyl" material from Flexcon.

The layer of adhesive 74 can be protected prior to use by a removablepaper sheet member 76. A planar, top insulating member 78, formed of aflexible planar plastic overlies the base member 62 and isolates thethermistor 70 as well as portions of the conductor 64a-64e along withthe conductors 66a-66e and 72 from the patient.

The removable sheet member 60 can be removably affixed to atransesophageal imaging probe, such as the probe 10 previouslydiscussed. The sheet member 60 is affixed to the probe 10 displaced fromthe distal end imaging transceiver 52 toward the proximal end of theprobe 10.

When the probe 10, carrying the sheet member 60, is positioned in theesophagus E of the patient, the location of the transmitter 52 can beoptimally set for carrying out the imaging function. Then, one or moreof the members of the plurality of electrodes 64a-64e can be recordingand/or selected for optimally carrying out an esophageal cardiac pacingfunction simultaneously with carrying out the imaging function. Further,at the same time the core temperature of the individual can becontinuously monitored using the thermistor 70.

FIG. 9 illustrates a unit 60a, coupled to the echocardiography probe 10,electrically connected via the eight connector 40 to an electrodeselector switch 46a and pacing unit 50. In addition, the thermistor 70is coupled via the connector 40 and the switch 46 to a temperaturesensor module 80 which for example could provide a digital display ofthe individual's temperature.

Without limitation and for example only the base member 62 could beformed of a vinyl plastic with a size on the order of 1 inch wide by 16to 20 inches long. The indicated electrode members corresponding to theelectrodes 64a-64e could be formed of deposited stainless steel. Silverconductive ink can be used to form the conductors 66a-66e and 72.Alternately, conducting foil or film can be applied to the base memberto form the conductors.

The size of the exposed dimensions of electrodes can be on the order of0.16 inches by 0.60 inches. It will be understood that while fiveelectrodes 64a-64e have been disclosed in FIG. 7 and eight have beendisclosed in FIG. 9, the exact number of electrodes is not a limitationof the present invention.

The electrode structure 60 can be permanently affixed to the probe 10.Alternately, in connection with a removably attachable form of thestructure 60 the way in which the attachment is carried out is not alimitation of the present invention. Instead of the disclosed layer ofadhesive, a vinyl plastic body member which will readily "cling" to theprobe 10 can be used. Mechanical means of attachment could also be used.

FIG. 10 illustrates an alternate electrode structure 60b. The structure60b includes a plurality of adhesive backed tabs 90. The tabs 90removably attach the structure 60b to an echo probe 10 by attaching to aportion of a sheet member 62a.

From the foregoing, it will be observed that numerous variations andmodifications may be effected without departing from the spirit andscope of the novel concept of the invention. It is to be understood thatno limitation with respect to the specific apparatus illustrated hereinis intended or should be inferred. It is, of course, intended to coverby the appended claims all such modifications as fall within the scopeof the claims.

What is claimed is:
 1. A disposable esophageal pacing and monitoringmember usable with an esophageal cardiac imaging probe comprising:aflexible, planar sheet member; a layer of adhesive carried on said sheetmember; a removable protective cover overlying said adhesive layer; aplurality of spaced apart planar electrodes carried on said sheetmember; and a temperature sensor carried on said sheet member.
 2. Amonitoring member as in claim 1 including a second planar sheet memberthat overlies, at least in part, said planar electrodes.
 3. A monitoringmember as in claim 1 including a plurality of elongated, flexible,conducting members with some members of said plurality coupled tocorresponding members of said plurality of electrodes with other membersof said plurality coupled to said temperature sensor.
 4. A disposableesophageal pacing and monitoring member usable with an esophagealcardiac imaging probe comprising:a flexible, planar sheet member; aplurality of adhesive backed tabs carried on said sheet member; aplurality of spaced apart planar electrodes carried on said sheetmember; and a temperature sensor carried on said sheet member with saidtabs usable to removably affix said sheet member to the probe.
 5. Adisposable esophageal member usable with an esophageal cardiac imagingprobe comprising:a flexible, planar sheet member; a plurality ofadhesive backed tabs carried on said sheet member; a plurality of spacedpart planar cardiac stimulating conductive members carried on said sheetmember; and a temperature sensor carried on said sheet member with saidtabs usable to removably affix said sheet member to the probe.
 6. Amember as in claim 5 including a second planar sheet member thatoverlies, at least in part, said planar stimulating members.
 7. Adisposable device that is attachable to an esophageal probe comprising:aflexible sheet member; attaching means on said sheet member forattaching said sheet member to the esophageal probe; a temperaturesensor on said sheet member and an electrode carried on said sheetmember.
 8. A disposable device that is attachable to an esophageal probecomprising:a flexible sheet member; attaching means on said sheet memberfor attaching said sheet member to the esophageal probe; a temperaturesensor on said sheet member and a plurality of electrodes carried onsaid sheet member.
 9. A device in accordance with claim 8 including asecond planar sheet member that overlies, at least in part, saidelectrodes.
 10. A device in accordance with claim 8 including aplurality of elongated, flexible conducting members wherein members ofsaid plurality are coupled to respective members of said plurality ofelectrodes.
 11. A device in accordance with claim 10 including anelectrical connector attached to said elongated conducting members at alocation displaced from said sheet member.
 12. A device in accordancewith claim 11 including a selector means for selecting at least one ofsaid electrodes, said selector means being couplable to said connector.13. A device insertable into an esophagus comprising:a flexible, planarelongated sheet member; a plurality of adhesive backed tabs carried onsaid sheet member; a plurality of spaced apart planar electrodes carriedon said sheet member; and a temperature sensor carried on said sheetmember.
 14. A multi-element electrode structure affixable to anessentially cylindrical esophageal probe which can then be inserted intothe esophagus of a patient, the electrode structure comprising:arectangular insulative sheet member having a selected length dimensionand a width dimension corresponding to the perimeter of the esophagealprobe; a plurality of spaced electrodes carried by said sheet member;adhesive means carried by said sheet member for affixing said member tothe probe; a plurality of elongated conducting members with each saidconducting member having an end in electrical contact with a respectiveone of said electrodes; and a temperature sensor carried on said sheetmember.
 15. A multi-element electrode in accordance with claim 14including an electrical connector displaced from said sheet member, saidelectrical connector being carried by said plurality of elongatedconducting members.
 16. A multi-element electrode in accordance withclaim 15 including means, couplable to said connector, for electricallyselecting at least one of said electrodes.
 17. A multi-element electrodein accordance with claim 15 including means for electrically selectingat least first and second of said electrodes.
 18. A multi-elementelectrode in accordance with claim 14 including a selector means forselecting at least one of said electrodes.
 19. A multi-element electrodestructure affixable to an essentially cylindrical esophageal probe whichcan then be inserted into the esophagus of a patient, the electrodestructure comprising:a rectangular insulative sheet member having aselected length dimension and a selected width dimension, said sheetmember being wrappable on the esophageal probe; means, carried by saidsheet member, for affixing said member to the probe; a plurality ofspaced, conducting electrode members carried by said sheet member; aplurality of elongated conducting members, each of said conductingmembers having an end in electrical contact with a respective one ofsaid electrode members; and a temperature sensor carried on said sheetmember.
 20. A multi-element structure in accordance with claim 19wherein each of said plurality of elongated conducting members carriesan electrical connector displaced from said sheet member.
 21. Amulti-element electrode structure in accordance with claim 19 includingmeans, couplable to said connector, for electrically selecting at leastone of said electrode members.
 22. A multi-element electrode structurein accordance with claim 19 including means for electrically selectingat least first and second of said electrode members.
 23. A multi-elementelectrode structure affixable to an essentially cylindrical esophagealprobe which can then be inserted into an esophagus of a patient, theelectrode structure comprising:an insulative sheet member; a pluralityof spaced electrodes carried by said sheet member; means for affixingsaid sheet member to the probe such that at least some of saidelectrodes substantially encircle said probe; a plurality of elongatedconducting members, each of said conducting members having an end inelectrical contact with a respective one of said electrodes; and atemperature sensor carried by said sheet member.